Garden Grove Thermal Runaway: Chemical Danger Meets a Tricky Weather Pattern

Added: 2026-05-25

[00:00:00]I'm meteorologist Bill Martin, West Coast meteorologist Bill Martin. Um, looking at the Garden Grove situation, it is Memorial Day weekend. There's a lot going on, but this story just doesn't want to go away. It's been going on for a couple days now. You've got over 40,000 50,000 people have been evacuated from the general vicinity of of the um GKN aerospace facility.

[00:00:23]um a six to 7,000galon tank of methylmethacryolate methylmethylacryolate MMA um it's highly flammable industrial used in making plastics and what happened is it appears what's happened what the best I can get the information is all over the map on this but the basic idea is it's a feedback loop they're calling it a thermal runaway reaction the chemical inside the tank start to react it starts to solidify that releases heat and the more it recently releases heat, the more that reaction keeps proliferating. And so, it's a feedback loop. And so, it's getting hotter and hotter and hotter.

[00:00:59]So, what's been going on the last days or so has been to try to keep the tank itself cool. They're basically throwing water on it, trying to keep the tank cool below at below or at 90°, I believe, to slow this process. But, you're really just buying time because at some point, this thing either explodes or leaks or you figure out a way to neutralize it. And that's again far outside the scope of my situation.

[00:01:24]But one of the things I wanted to point out was the air quality and how it matters in this zone. When I talk about air quality, when I talk about the meteorology in this zone, this is Los Angeles area. This is this morning. And you see all the fog, right? And how far inland it is. So there is an inversion, which is the last, not the last thing you want, but it's what you got. You've got an inversion and the fog, but it's a deeper inversion. So we'll explore that.

[00:01:50]The evacuation zones are here. Let's come in a little closer. Um, I'll show you exactly what we're looking at. Um, and again, you got to realize this is an urban urban area. It's it's zoned industrial clearly, but so here, let me back out again. This is Google Earth.

[00:02:06]And that's Los Angeles area, Pasadena, Los Angeles. We're coming into Garden Grove.

[00:02:13]And we'll we'll and you can see the area. You can kind of see the industry around it, but you also see plenty of homes within two or three blocks. And the blast zone, I've seen some concentric rings on the blast zone if this thing explodes. Uh the blast zone extends out two or three blocks in all directions. So, for whatever that's worth, um I say blast zone, I don't Is that going to happen? Who knows? I mean, but that's the thing is who knows? So I'm looking at if it does if it explodes or if it continues to leak those two um outcomes are there's going to create toxicity plume of some extent. So we're going to look at the depth of the marine layer, the the depth of the inversion and the wind directions over the next couple of days to determine just what you can expect or what we could expect and how how how safe you would be depending on where you are. Um this is the zone. Let's see. This is the agency.

[00:03:07]Let me find the railroad tracks. H, there they are. Okay. So, here's the tank. This is AK or GKN Enterprises.

[00:03:17]And this is the main tank, I believe, that they're working on, right?

[00:03:21]And so in here is the methylchry, the MMA. These adjacent tanks, as one of you pointed out to me the other day, most certainly have stuff in there that's not good either. So, an explosion might compromise those as well. Uh, and you can see it's a major industrial area because you've got railroad tracks running around this thing obviously to transport these chemicals. And then if you back it out all the way, you can see the landscape and the landscape is pretty flat. There's not a lot of topography and there's a lot a lot of people in Garden Grove. And so they've evacuated 40 or 50,000 people. Um, they've evacuated nearby schools. Some are some are staying with friends and family. Others are using emergency shelters set up in the nearby city of Anaheim, Huntington Beach, Fountain Valley, and La Palma. Hotels around Disneyland have offered some emergency stuff. I'm just trying to I mean, where do where do you what do you do with 40,000 people in the heart of a city?

[00:04:16]There's not a ton of hotels. I mean, it take a lot of hotels to fill up 40,000 people. They're using some high schools as well. Um, the official emergency page with evacuation maps and shelter info is in the Garden Grove emergency information page. So, I guess they have a page you can access. But, um, so that so that's that's the lay of the land.

[00:04:37]This is the lay of the weather and how it could impact. So, again, here's the first thing I see is a deeper inversion.

[00:04:43]Deeper inversion means there's more room. this area. This is the Los Angeles basin in here that known it's it's legendary for its inversions. It's shallow inversions, smog, bad air quality. You know the story. Today it's a little bit deeper. It's than it was the last couple of days. So meaning deeper it's the the marine layer is up around almost 2,000 ft. So it's almost like a low cloud. So there's mixing available in the middle section there, which would be in this case if any fumes are leaking out. You're going to have the ability for that to not just be living in a 500 ft, 600 foot inversion, like just you got triple that, right?

[00:05:24]You've got a couple thousand feet of of air. So room for circulation, which is very important. This is Mount Wilson east. And again, Mount Wilson's at uh 5600 ft. So we're 5,600 feet here.

[00:05:38]garden grove down here and you can see them the if that's 56 if this is 5600 feet that the depth of the inversion because that's where the fog is, right?

[00:05:47]The depth of the inversion here is yeah couple thousand feet easy. So that's in in a in a way it's good news. Same thing here. You're seeing this from Harvard um up the Harvard mountain area up um kind of just up in outside the basin but you can see the base. So it's a very deep inversion. That's the takeaway here. And with that in mind, you look at the winds at the surface and you go, "Okay, well, here's Garden Grove right here. It's 71 degrees. This is going to be this afternoon's forecast highs." And you see these little wind vectors. So, not much.

[00:06:20]The wind I think I got to take on. I think the winds are going to be sustained. Yeah. 10 miles an hour southwest. They're the general wind direction is southwest, which is this direction. So, the winds are going to blow this way for the next couple of days. and 10 miles an hour. Not bad. Not bad. If you had a real shallow inversion, 600, 700 feet, you wouldn't have those winds. You'd just be flat dead calm and then if this thing starts leaking, it's going to concentrate. The idea in this being just my experiences with the Martinez refinery and the Richmond refinery working in the Bay Area all these years when we'd have some kind of a chemical issue which we've had, you really do want um the the inversion spread out because it pushes the air and clears clears it more rapidly and just puts it up in a higher place and just really makes a huge difference obviously obviously in concentrations. So, the winds are doing the right thing thus far, and they will for the next couple of days. Here's the inversion. This is Garden Grove right here. This is the computer model um version of the sounding. And this is the atmosphere warming or cooling as you go up and then it warms here. Starts to warm. So, that that's the top of the inversion. That's what we were looking at right right there. And right there, that's the top of the inversion. So that's what you're looking at when you look at the top when when the the red line meets the blue line. That's where there's a cloud formed. So this whole layer is clouds, but the inversion starts the bottom of the inversion is right around 2,000 ft. So that in in many ways is very fortunate. You also have a little not a lot of wind. You got, you know, five knot, 10 knot winds at best in this zone, but that's a lot better than having a huge cap. So that's how it looks right now or this this afternoon. This is how it's going to look or pardon me. That's how it looks right now. This is how it's going to look this afternoon. The inversion kind of breaks up. So the due point the the blue and the red get further apart meaning that the clouds are going to burn. That's a burnoff. You know when the fog burns off and when that happens the vertical mixing will start to occur.

[00:08:33]And the so this afternoon you're going to see a bit of clearing. you're going to see the wind starting to go vertically and continuing to blow out of the southwest, which again is a would be a fortunate thing. Um, in given the time of year, the topography of the basin and so on. So, this is uh the purple air. This just measures particulate matter. I'm just kind of looking at it as a guide to oh, okay.

[00:09:03]Um, the air quality is kind of like what we thought. Like if you've been with me the last couple days, we've been looking at air quality in LA. It's been reds and yellows and oranges. So this air quality today by purple air just showing basic industrial pollutants and things. This is particulate matter 2.5. Um it shows that it's it's a little deeper. So it's it it's so much better than had this occurred a couple days ago. Um and so this is the wind forecast for the next couple of days. And basically you're just looking at winds that are going to be blowing in this. Let's see. This area is point conception. So here in this area, you're looking at kind of a slight southwest wind and that's how it goes the next couple of days. So the story here, let's take a look. I don't want to miss anything. So the story is this stuff, this chemical, it's a runaway thermal reaction. And that's what's the problem is now. It's like it either explodes or it leaks or they figure out a way to neutralize it. But once things, it's like cement. Um once it gets once it starts to solidify it releases a lot of heat and the heat the releasing of heat continues the the chain reaction of event of of heating and so that's why you're just trying to keep it cold cold.

[00:10:11]It's like it's like a cistheian task in some ways because um I think the pressure in that tank is building that the I I've heard that as it solidifies it gets smaller but it gets hotter. So you see you can check in on that. So, um, what else we got? Uh, the zone generally covers the area between Ball Road and Tras Avenue between View and Dale Street. Authorities say about 15% of the residents have just didn't want to leave, but now they're they're kind of rethinking it. So, they've evacuated four 40 to 50,000 people. No toxic plume yet, but the risk remains high. Air monitoring so far has reportedly shown no major toxic release yet, which is good news. But officials are worried that if the tank fails suddenly, a toxic vapor cloud, and this is where the weather comes in, a toxic vapor cloud could spread quickly. MMA exposure can irritate lungs, eyes, and skin, and become dangerous in high concentrations.

[00:11:08]Newsome, Governor Nuome declared a state of emergency for Orange County yesterday. Um um are now involved. They got the state involved obviously. Um and then they what they do with the 40 or 50,000 people are staying with friends and family and local JC's. So this story is is um ongoing. It's it's kinetic. Uh it's a feedback loop of thermal heating and chain reaction inside this tank.

[00:11:35]They got to figure out how to make it not explode or not leak. Either way, if it does explode or does leak, you're going to have this this this toxic plume potentially or not good for you plume in this middle of this urban environment that's going to drift. But 40,000 50,000 people have been evacuated from zones close. um in the envir I guess my whole task here is to say if that happens in the next two days um from what we can see here in the meteorology it's going to be there's going to be some wind and the inversion is not too shallow. I mean that's the best news I can offer you and it's not the best there's better news you could have it you know they could neutralize it but that's how that goes. I just wanted to get on record with that only because it's it's such a huge story, but it's literally getting not a lot national news coverage. I'm like, it's a big deal. It's a big deal. The the evacuation of all those people. Um and then the ticking time palm aspect to it.

[00:12:32]I mean, the the firefighter a couple days ago, he got on and go say, "Listen, this thing either explodes or blows out toxic plume plumes everywhere." I think there might be a third option if they can figure out something to neutralize that chemical reaction, but again, that's out beside the scope of my um expertise. Okay, just checking in. We'll talk to you tomorrow. We'll do West Coast weather. We'll do the weather forecast for the coming week. I'll see you back here.